研究目的
To develop and validate a non-empirical generalized gradient approximation (GGA) exchange density functional that performs as well as the SCAN meta-GGA on standard thermochemistry tests, yields Kohn-Sham eigenvalues useful for DFT ionization potential theorem values, and enables accurate TD-DFT calculations of polarizabilities, hyper-polarizabilities, and one-fermion excited states without modification of the long-range behavior of the exchange potential.
研究成果
The NCAP GGA X functional requires no experimental parametrization, delivers a physically sensible X potential with approximately correct behavior at large finite distances, respects the global Lieb-Oxford bound, and provides superior or competitive performance on standard thermochemical test sets and TD-DFT response properties. It represents a significant advancement in the development of non-empirical GGA functionals.
研究不足
The NCAP functional's exchange potential goes as ?c/r with an estimated constant c of around 0.3, which is not exactly ?1/r as in the exact case. The functional's performance on weakly bonded systems is slightly worse than some other functionals.